In order to meet the challenges of wireless broadband technology and keep the pioneering advantages of the third generation partnership project (The 3rd Generation Partnership Project, 3GPP) network, the 3GPP developed a long term evolution (Long Term Evolution, LTE) scheme at the end of 2004. A new mobile communication network architecture is defined under the guidance of the evolution scheme, the architecture only retains a packet switched (Packet Switched, PS) domain, and thus the architecture is called an evolved packet system (corresponding English full title is Evolved Packet System, EPS or System Architecture Evolution, SAE). The architecture of an LTE system is shown in FIG. 1, wherein a serving GPRS support node SGSN (Serving GPRS SUPPORT NODE) is an important part of a core network packet domain device, a home subscriber server HSS (Home Subscriber Server) is an important part of a central control layer, a GSM and EDGE radio access network GERAN (GSM EDGE Radio Access Network) and a global universal terrestrial radio access network UTRAN (Universal Terrestrial Radio Access) provide a radio access manner respectively, an evolved universal terrestrial radio access network E-UTRAN (Evolved Universal Terrestrial Radio Access Network) is an evolved base station eNB and is responsible for modulating and demodulating data. A serving gateway (Serving Gateway) and a packet data network gateway (Packet Data Network Gateway) are evolved gateways, and are responsible for forwarding data packets. A mobility management entity (Mobility Management Entity) is a signaling control entity of an evolved system and is responsible for such functions as authentication, mobility management and the like, a policy and charging rules function PCRF (Policy and Charging Rules Function) is a decision point of the service data flows and IP bearer resources policy and the charging control policy. An evolved network does not provide a traditional circuit-switched voice function, but only provides a high rate data bearer service. As shown in FIG. 1, the evolved system may further support intercommunication between the third generation universal terrestrial radio access network (Universal Terrestrial Radio Access Network) of the 3GPP and the 2.5th generation radio access network (GSM (GPRS)/EDGE Radio Access Network) of the 3GPP.
As shown in FIG. 2, the third generation partnership project (The 3rd Generation Partnership Project) and the third generation partnership project 2 (3GPP2) further define an intercommunication standard of a service between an LTE (Long Term Evolution) network and a CDMA (Code Division Multiple Access) high rate packet data (High Rate Packet Data, HRPD) network, and support the CDMA HRPD network to access an evolved packet core network (Evolved Packet Core, EPC) and to switch data services.
In the prior art, under the intercommunication architecture of packet data services between the above-mentioned LTE network and the CDMA HRPD network, a user equipment (User Equipment, UE) may switch between two networks, however, the user equipment may only implement the data services in one system (LTE or CDMA HRPD) at one moment, so that the network resources could not be fully utilized, and a data rate of a user is low.